In this post I’m going to show you how to diagnose SQL exceptions using memory dumps. Imagine you have a web application deployed on a production server. Your application is using Elmah configured to log all exceptions to a dedicated table. One day you receive information that users are unable to make orders and in the Elmah log there are lots of
SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM. at System.Data.SqlClient.TdsParser.TdsExecuteRPC(_SqlRPC rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc, Boolean sync, TaskCompletionSource`1 completion, Int32 startRpc, Int32 startParam) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task&amp; task, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task&amp; task, Boolean asyncWrite) ...
No more information available. If you are using NHibernate you may turn on SQL logging but, if you have thousands of users, this will have a negative impact on the application responsiveness. Another idea might be to use ADO.NET ETW logs – even though this way we will minimize the performance drop, it’s still not a perfect solution. ETW logs weigh hundreds of MB and contain a tremendous amount of information, which you need to filter and analyze. I plan to write about this type of logging in the future. For now, let’s take a third approach: create a production memory dump when the application breaks and analyze it locally in the debugger.
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